tercul-backend/internal/repositories/cached_repository.go

package repositories

import (
	"context"
	"fmt"
	"time"

	"gorm.io/gorm"
	"tercul/internal/platform/cache"
	"tercul/internal/platform/log"
)

// simpleKeyGenerator implements the cache.KeyGenerator interface
type simpleKeyGenerator struct {
	prefix string
}

// EntityKey generates a key for an entity by ID
func (g *simpleKeyGenerator) EntityKey(entityType string, id uint) string {
	return g.prefix + entityType + ":id:" + fmt.Sprintf("%d", id)
}

// ListKey generates a key for a list of entities
func (g *simpleKeyGenerator) ListKey(entityType string, page, pageSize int) string {
	return g.prefix + entityType + ":list:" + fmt.Sprintf("%d:%d", page, pageSize)
}

// QueryKey generates a key for a custom query
func (g *simpleKeyGenerator) QueryKey(entityType string, queryName string, params ...interface{}) string {
	key := g.prefix + entityType + ":" + queryName
	for _, param := range params {
		key += ":" + fmt.Sprintf("%v", param)
	}
	return key
}

// CachedRepository wraps a BaseRepository with caching functionality
type CachedRepository[T any] struct {
	repo  BaseRepository[T]
	cache cache.Cache
	keyGenerator cache.KeyGenerator
	entityType   string
	cacheExpiry  time.Duration
	cacheEnabled bool
}

// NewCachedRepository creates a new CachedRepository
func NewCachedRepository[T any](
	repo BaseRepository[T],
	cache cache.Cache,
	keyGenerator cache.KeyGenerator,
	entityType string,
	cacheExpiry time.Duration,
) *CachedRepository[T] {
	if keyGenerator == nil {
		// Create a simple key generator
		keyGenerator = &simpleKeyGenerator{prefix: "tercul:"}
	}

	if cacheExpiry == 0 {
		cacheExpiry = 1 * time.Hour // Default expiry of 1 hour
	}

	return &CachedRepository[T]{
		repo:         repo,
		cache:        cache,
		keyGenerator: keyGenerator,
		entityType:   entityType,
		cacheExpiry:  cacheExpiry,
		cacheEnabled: true,
	}
}

// EnableCache enables caching
func (r *CachedRepository[T]) EnableCache() {
	r.cacheEnabled = true
}

// DisableCache disables caching
func (r *CachedRepository[T]) DisableCache() {
	r.cacheEnabled = false
}

// Create adds a new entity to the database
func (r *CachedRepository[T]) Create(ctx context.Context, entity *T) error {
	err := r.repo.Create(ctx, entity)
	if err != nil {
		return err
	}

	// Invalidate cache for this entity type
	if r.cacheEnabled {
		if redisCache, ok := r.cache.(*cache.RedisCache); ok {
			if err := redisCache.InvalidateEntityType(ctx, r.entityType); err != nil {
				log.LogWarn("Failed to invalidate cache",
					log.F("entityType", r.entityType),
					log.F("error", err))
			}
		}
	}

	return nil
}

// CreateInTx creates an entity within a transaction
func (r *CachedRepository[T]) CreateInTx(ctx context.Context, tx *gorm.DB, entity *T) error {
	return r.repo.CreateInTx(ctx, tx, entity)
}

// GetByID retrieves an entity by its ID
func (r *CachedRepository[T]) GetByID(ctx context.Context, id uint) (*T, error) {
	if !r.cacheEnabled {
		return r.repo.GetByID(ctx, id)
	}

	cacheKey := r.keyGenerator.EntityKey(r.entityType, id)

	var entity T
	err := r.cache.Get(ctx, cacheKey, &entity)
	if err == nil {
		// Cache hit
		log.LogDebug("Cache hit",
			log.F("entityType", r.entityType),
			log.F("id", id))
		return &entity, nil
	}

	// Cache miss, get from database
	log.LogDebug("Cache miss",
		log.F("entityType", r.entityType),
		log.F("id", id))

	entity_ptr, err := r.repo.GetByID(ctx, id)
	if err != nil {
		return nil, err
	}

	// Store in cache
	if err := r.cache.Set(ctx, cacheKey, entity_ptr, r.cacheExpiry); err != nil {
		log.LogWarn("Failed to cache entity",
			log.F("entityType", r.entityType),
			log.F("id", id),
			log.F("error", err))
	}

	return entity_ptr, nil
}

// GetByIDWithOptions retrieves an entity by its ID with query options
func (r *CachedRepository[T]) GetByIDWithOptions(ctx context.Context, id uint, options *QueryOptions) (*T, error) {
	// For complex queries with options, we don't cache as the cache key would be too complex
	return r.repo.GetByIDWithOptions(ctx, id, options)
}

// Update updates an existing entity
func (r *CachedRepository[T]) Update(ctx context.Context, entity *T) error {
	err := r.repo.Update(ctx, entity)
	if err != nil {
		return err
	}

	// Invalidate cache for this entity
	if r.cacheEnabled {
		// Invalidate specific entity cache
		cacheKey := r.keyGenerator.EntityKey(r.entityType, 0) // We don't have ID here, so invalidate all
		if err := r.cache.Delete(ctx, cacheKey); err != nil {
			log.LogWarn("Failed to invalidate entity cache",
				log.F("entityType", r.entityType),
				log.F("error", err))
		}

		// Invalidate list caches
		if redisCache, ok := r.cache.(*cache.RedisCache); ok {
			if err := redisCache.InvalidateEntityType(ctx, r.entityType); err != nil {
				log.LogWarn("Failed to invalidate cache",
					log.F("entityType", r.entityType),
					log.F("error", err))
			}
		}
	}

	return nil
}

// UpdateInTx updates an entity within a transaction
func (r *CachedRepository[T]) UpdateInTx(ctx context.Context, tx *gorm.DB, entity *T) error {
	return r.repo.UpdateInTx(ctx, tx, entity)
}

// Delete removes an entity by its ID
func (r *CachedRepository[T]) Delete(ctx context.Context, id uint) error {
	err := r.repo.Delete(ctx, id)
	if err != nil {
		return err
	}

	// Invalidate cache for this entity
	if r.cacheEnabled {
		cacheKey := r.keyGenerator.EntityKey(r.entityType, id)
		if err := r.cache.Delete(ctx, cacheKey); err != nil {
			log.LogWarn("Failed to invalidate entity cache",
				log.F("entityType", r.entityType),
				log.F("id", id),
				log.F("error", err))
		}

		// Invalidate list caches
		if redisCache, ok := r.cache.(*cache.RedisCache); ok {
			if err := redisCache.InvalidateEntityType(ctx, r.entityType); err != nil {
				log.LogWarn("Failed to invalidate cache",
					log.F("entityType", r.entityType),
					log.F("error", err))
			}
		}
	}

	return nil
}

// DeleteInTx removes an entity by its ID within a transaction
func (r *CachedRepository[T]) DeleteInTx(ctx context.Context, tx *gorm.DB, id uint) error {
	return r.repo.DeleteInTx(ctx, tx, id)
}

// List returns a paginated list of entities
func (r *CachedRepository[T]) List(ctx context.Context, page, pageSize int) (*PaginatedResult[T], error) {
	if !r.cacheEnabled {
		return r.repo.List(ctx, page, pageSize)
	}

	cacheKey := r.keyGenerator.ListKey(r.entityType, page, pageSize)

	var result PaginatedResult[T]
	err := r.cache.Get(ctx, cacheKey, &result)
	if err == nil {
		// Cache hit
		log.LogDebug("Cache hit for list",
			log.F("entityType", r.entityType),
			log.F("page", page),
			log.F("pageSize", pageSize))
		return &result, nil
	}

	// Cache miss, get from database
	log.LogDebug("Cache miss for list",
		log.F("entityType", r.entityType),
		log.F("page", page),
		log.F("pageSize", pageSize))

	result_ptr, err := r.repo.List(ctx, page, pageSize)
	if err != nil {
		return nil, err
	}

	// Store in cache
	if err := r.cache.Set(ctx, cacheKey, result_ptr, r.cacheExpiry); err != nil {
		log.LogWarn("Failed to cache list",
			log.F("entityType", r.entityType),
			log.F("page", page),
			log.F("pageSize", pageSize),
			log.F("error", err))
	}

	return result_ptr, nil
}

// ListWithOptions returns entities with query options
func (r *CachedRepository[T]) ListWithOptions(ctx context.Context, options *QueryOptions) ([]T, error) {
	// For complex queries with options, we don't cache as the cache key would be too complex
	return r.repo.ListWithOptions(ctx, options)
}

// ListAll returns all entities (use with caution for large datasets)
func (r *CachedRepository[T]) ListAll(ctx context.Context) ([]T, error) {
	if !r.cacheEnabled {
		return r.repo.ListAll(ctx)
	}

	cacheKey := r.keyGenerator.QueryKey(r.entityType, "listAll")

	var entities []T
	err := r.cache.Get(ctx, cacheKey, &entities)
	if err == nil {
		// Cache hit
		log.LogDebug("Cache hit for listAll",
			log.F("entityType", r.entityType))
		return entities, nil
	}

	// Cache miss, get from database
	log.LogDebug("Cache miss for listAll",
		log.F("entityType", r.entityType))

	entities, err = r.repo.ListAll(ctx)
	if err != nil {
		return nil, err
	}

	// Store in cache
	if err := r.cache.Set(ctx, cacheKey, entities, r.cacheExpiry); err != nil {
		log.LogWarn("Failed to cache listAll",
			log.F("entityType", r.entityType),
			log.F("error", err))
	}

	return entities, nil
}

// Count returns the total number of entities
func (r *CachedRepository[T]) Count(ctx context.Context) (int64, error) {
	if !r.cacheEnabled {
		return r.repo.Count(ctx)
	}

	cacheKey := r.keyGenerator.QueryKey(r.entityType, "count")

	var count int64
	err := r.cache.Get(ctx, cacheKey, &count)
	if err == nil {
		// Cache hit
		log.LogDebug("Cache hit for count",
			log.F("entityType", r.entityType))
		return count, nil
	}

	// Cache miss, get from database
	log.LogDebug("Cache miss for count",
		log.F("entityType", r.entityType))

	count, err = r.repo.Count(ctx)
	if err != nil {
		return 0, err
	}

	// Store in cache
	if err := r.cache.Set(ctx, cacheKey, count, r.cacheExpiry); err != nil {
		log.LogWarn("Failed to cache count",
			log.F("entityType", r.entityType),
			log.F("error", err))
	}

	return count, nil
}

// CountWithOptions returns the count with query options
func (r *CachedRepository[T]) CountWithOptions(ctx context.Context, options *QueryOptions) (int64, error) {
	// For complex queries with options, we don't cache as the cache key would be too complex
	return r.repo.CountWithOptions(ctx, options)
}

// FindWithPreload retrieves an entity by its ID with preloaded relationships
func (r *CachedRepository[T]) FindWithPreload(ctx context.Context, preloads []string, id uint) (*T, error) {
	// For preloaded queries, we don't cache as the cache key would be too complex
	return r.repo.FindWithPreload(ctx, preloads, id)
}

// GetAllForSync returns entities in batches for synchronization
func (r *CachedRepository[T]) GetAllForSync(ctx context.Context, batchSize, offset int) ([]T, error) {
	// For sync operations, we don't cache as the data is constantly changing
	return r.repo.GetAllForSync(ctx, batchSize, offset)
}

// Exists checks if an entity exists by ID
func (r *CachedRepository[T]) Exists(ctx context.Context, id uint) (bool, error) {
	// For existence checks, we don't cache as the result can change frequently
	return r.repo.Exists(ctx, id)
}

// BeginTx starts a new transaction
func (r *CachedRepository[T]) BeginTx(ctx context.Context) (*gorm.DB, error) {
	return r.repo.BeginTx(ctx)
}

// WithTx executes a function within a transaction
func (r *CachedRepository[T]) WithTx(ctx context.Context, fn func(tx *gorm.DB) error) error {
	return r.repo.WithTx(ctx, fn)
}